4,230 research outputs found
Universality and Non-Perturbative Definitions of 2D Quantum Gravity from Matrix Models
The universality of the non-perturbative definition of Hermitian one-matrix
models following the quantum, stochastic, or -like stabilization is
discussed in comparison with other procedures. We also present another
alternative definition, which illustrates the need of new physical input for
matrix models to make contact with 2D quantum gravity at the
non-perturbative level.Comment: 20 page
Variations on the adiabatic invariance: the Lorentz pendulum
We analyze a very simple variant of the Lorentz pendulum, in which the length
is varied exponentially, instead of uniformly, as it is assumed in the standard
case. We establish quantitative criteria for the condition of adiabatic changes
in both pendula and put in evidence their substantially different physical
behavior with regard to adiabatic invariance.Comment: To appear in American Journal of Physic
Invisibility and PT Symmetry: A Simple Geometrical Viewpoint
We give a simplified account of the properties of the transfer matrix for a
complex one-dimensional potential, paying special attention to the particular
instance of unidirectional invisibility. In appropriate variables, invisible
potentials appear as performing null rotations, which lead to the
helicity-gauge symmetry of massless particles. In hyperbolic geometry, this can
be interpreted, via M\"{o}bius transformations, as parallel displacements, a
geometric action that has no Euclidean analogy.Comment: 13 pages. No figure. Accepted for publication in Symmetr
The many facets of the Fabry-Perot
We address the response, both in amplitude and intensity, of a Fabry-Perot
from a variety of viewpoints. These complementary pictures conspire to achieve
a comprehensive and consistent theory of the operation of this system.Comment: 15 pages, 9 figure
Charged-Current Neutral Pion production at SciBooNE
SciBooNE, located in the Booster Neutrino Beam at Fermilab, collected data
from June 2007 to August 2008 to accurately measure muon neutrino and
anti-neutrino cross sections on carbon below 1 GeV neutrino energy. SciBooNE is
studying charged current interactions. Among them, neutral pion production
interactions will be the focus of this poster. The experimental signature of
neutrino-induced neutral pion production is constituted by two electromagnetic
cascades initiated by the conversion of the neutral pion decay photons, with an
additional muon in the final state for CC processes.
In this poster, I will present how we reconstruct and select charged-current
muon neutrino interactions producing neutral pions in SciBooNE.Comment: NuInt09 poster proceedings, 4 page
Neutrino interactions with nuclei
We present a model for neutrino-nucleus scattering in the energy region
relevant for present and forthcoming neutrino-oscillation experiments. The
model is based on the RPA treatment of the nuclear responses in the
quasi-elastic and Delta-resonance region. It includes also in a
phenomenological way nucleon knock-out. It aims at the description, within a
single framework, of several final state channels i.e. quasi-elastic,
incoherent and coherent one-pion production and two- or several-nucleon
knock-out.Comment: To appear in the proceedings of 6th International Workshop on
Neutrino-Nucleus Interactions in the Few-GeV Region (NuInt09), Sitges, Spain,
18 - 22 May 200
Interim outcomes of mechanical thrombectomy for deep vein thrombosis from the all-comer CLOUT registry
OBJECTIVES: The multicenter, prospective, single arm CLOUT registry assesses the safety and effectiveness of the ClotTriever System (Inari Medical, Irvine, CA) for the treatment of acute and nonacute lower extremity deep vein thrombosis (DVT) in all-comer patients. Reported here are the outcomes of the first 250 patients.
METHODS: All-comer patients with lower extremity DVT were enrolled, including those with bilateral DVT, those with previously failed DVT treatment, and regardless of symptom duration. The primary effectiveness end point is complete or near-complete (≥75%) thrombus removal determined by independent core laboratory-adjudicated Marder scores. Safety outcomes include serious adverse events through 30 days and clinical outcomes include post-thrombotic syndrome severity, symptoms, pain, and quality of life through 6 months.
RESULTS: The median age was 62 years and 40% of patients had contraindications to thrombolytics. A range of thrombus chronicity (33% acute, 35% subacute, 32% chronic) was observed. No patients received thrombolytics and 99.6% were treated in a single session. The median thrombectomy time was 28 minutes. The primary effectiveness end point was achieved in 86% of limbs. Through 30 days, one device-related serious adverse event occurred. At 6 months, 24% of patients had post-thrombotic syndrome. Significant and sustained improvements were observed in all clinical outcomes, including the Revised Venous Clinical Severity Score, the numeric pain rating scale, and the EuroQol Group 5-Dimension Self-Report Questionnaire.
CONCLUSIONS: The 6-month outcomes from the all-comer CLOUT registry with a range of thrombus chronicities demonstrate favorable effectiveness, safety, and sustained clinical improvements
Metallicity inhomogeneities in local star-forming galaxies as sign of recent metal-poor gas accretion
We measure the oxygen metallicity of the ionized gas along the major axis of
seven dwarf star-forming galaxies. Two of them, SDSSJ1647+21 and SDSSJ2238+14,
show 0.5 dex metallicity decrements in inner regions with enhanced
star-formation activity. This behavior is similar to the metallicity drop
observed in a number of local tadpole galaxies by Sanchez Almeida et al. (2013)
and interpreted as showing early stages of assembling in disk galaxies, with
the star formation sustained by external metal-poor gas accretion. The
agreement with tadpoles has several implications: (1) it proves that galaxies
other than the local tadpoles present the same unusual metallicity pattern. (2)
Our metallicity inhomogeneities were inferred using the direct method, thus
discarding systematic errors usually attributed to other methods. (3) Taken
together with the tadpole data, our findings suggest a threshold around one
tenth the solar value for the metallicity drops to show up. Although galaxies
with clear metallicity drops are rare, the physical mechanism responsible for
them may sustain a significant part of the star-formation activity in the local
Universe. We argue that the star-formation dependence of the mass-metallicity
relationship, as well as other general properties followed by most local disk
galaxies, are naturally interpreted as side effects of pristine gas infall.
Alternatives to the metal poor gas accretion are examined too.Comment: Accepted for publication in ApJ. 10 pages. 5 Fig
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